Synergistic Plasmonic Responses of Multi-Shaped Au Nanostructures Hybridized with Few-Layer WS2 Nanosheets for Organic Solar Cells

Raising the photocurrent and successively achieving a high power conversion efficiency (PCE) in organic solar cells (OSCs) with physically thin photoactive layers is usually a highly challenging task because of their excitonic nature. Herein, we utilized the synergistic plasmonic effects of multi-shaped Au nanostructures (diameter/edge length ∼50 nm) hybridized with few-layer WS2 nanosheets in improving the photocurrent of fullerene and non-fullerene-based OSCs. A PCE enhancement of more than 15% and an external quantum efficiency improvement in a broad wavelength range of 350–700 nm were demonstrated by incorporating these Au-WS2 nanohybrids as an interlayer between hole transport and photoactive layers. The PCE enhancement was mainly due to the improved photocurrent (∼12.41%) via broad-range plasmonic effects of Au nanostructures. Finite-difference time-domain simulations were performed to comprehensively study the plasmonic responses, such as scattering efficiency, direction-dependent scattering, and near-field effects of individual nanostructures. The effective plasmonic range over 350–700 nm and more than 50% forward light scattering indicated that these hybridized Au nanostructures are highly suitable candidates to couple the incident light into the active layer. Near-field intensity enhancement and subsequent enhancement in absorption density confirmed the elevated local density of optical states in Au-WS2 nanohybrid-based devices. Therefore, the present study emphasizes the role of hybridized Au-WS2 nanostructures in improving the light-harvesting capability of OSCs in a broad wavelength range, hence attaining a significant improvement in device photocurrent.